Various medication injection pen devices are known in the prior art. These prior art devices sometimes include features for enabling a user to correct a dose that has been set too large, which may be referred to as “dial back”. Another feature that may be provided by some of the prior art devices is the ability to control a last dose of a medication cartridge such that a user cannot set a dose greater than the remaining amount of medication in the cartridge. This feature is referred to as last dose control or last dose management. Both of these features are desired by users of such pen devices; however, the prior art devices do not satisfactorily meet these needs. Many prior art devices may provide one of these features, but not both. Further, many of the prior art devices require additional steps for performing dial back, which are cumbersome and not intuitive to the user. Thus, there is a need in the art to provide improved functionality of dial back and last dose control mechanisms together in a medication injection pen.
SUMMARY OF EMBODIMENTS OF THE INVENTION
Exemplary embodiments of the present invention address at least the above problems and/or disadvantages and provide at least the advantages described below.
Accordingly, a first exemplary embodiment of the present invention provides a medication injection pen comprising a housing, for housing a dose set knob, a leadscrew, a driver, a setback member, and a dose stop member. The dose set knob is rotatable with respect to said housing to set a desired injection dose, and comprises at least one internal thread. The leadscrew includes a thread element by which it is advanceable in a first direction via a corresponding thread engagement, said first direction being that which expels medication from a cartridge. The driver is rotationally fixed to said leadscrew for preventing relative rotation therebetween, said driver being rotatable in a first direction to rotate and advance said leadscrew in said first direction. The setback member is rotationally fixed to said driver for preventing relative rotation therebetween. The dose stop member is rotationally fixed to said setback member and comprises an external thread in threaded engagement with said internal thread of said dose set knob, said dose stop member being axially movable relative to said dose set knob when said dose set knob is rotated relative to said setback member, and wherein axial movement of said dose stop member limits the user from setting a dose that is greater than an injectable volume of medication remaining in the cartridge.
According to another exemplary embodiment of the present invention a medication injection pen is provided comprising a housing, for housing a dose set knob, a leadscrew, a driver, a setback member, and a dose stop member. The dose set knob is rotatable with respect to said housing to set a desired injection dose. The leadscrew includes a thread element by which it is advanceable in a first direction via a corresponding thread engagement, said first direction being that which expels medication from a cartridge. The driver is rotationally fixed to said leadscrew for preventing relative rotation therebetween, said driver being rotatable in a first direction to rotate and advance said leadscrew in said first direction. The setback member is rotationally fixed to said driver for preventing relative rotation therebetween, and is provided with an external thread thereon. The dose stop member is rotationally fixed to said dose set knob and comprises an internal thread in threaded engagement with said external thread of said setback member, said dose stop member being axially movable relative to said dose set knob when said dose set knob is rotated relative to said setback member, and wherein axial movement of said dose stop member limits a user from setting a dose that is greater than an injectable volume of medication remaining in the cartridge.
According to yet another exemplary embodiment of the present invention a medication injection pen is provided comprising a housing, for housing a dose set knob, a leadscrew, a driver, a setback member, and a dose stop member. The dose set knob is rotatable with respect to said housing to set a desired injection dose. The leadscrew includes a thread element by which it is advanceable in a first direction via a corresponding thread engagement, said first direction being that which expels medication from a cartridge. The driver is rotationally fixed to said leadscrew for preventing relative rotation therebetween, said driver being rotatable in a first direction to rotate and advance said leadscrew in said first direction. The setback member is rotationally fixed to said driver for preventing relative rotation therebetween. The dose stop member is rotationally fixed to said dose set knob and comprises an internal thread in threaded engagement with said thread of said leadscrew, said dose stop member being axially movable relative to said dose set knob when said dose set knob is rotated relative to said setback member, and wherein axial movement of said dose stop member limits a user from setting a dose that is greater than an injectable volume of medication remaining in the cartridge.
According to yet another exemplary embodiment of the present invention a medication injection pen is provided comprising a housing, for housing a dose set knob, a leadscrew, a driver, a setback member, and a click element. The dose set knob is rotatable with respect to said housing to set a desired injection dose. The leadscrew includes a thread element by which it is advanceable in a first direction via a corresponding thread engagement, said first direction being that which expels medication from a cartridge. The driver is rotationally fixed to said leadscrew for preventing relative rotation therebetween, said driver being rotatable in a first direction to rotate and advance said leadscrew in said first direction. The setback member is rotationally fixed to said driver for preventing relative rotation therebetween. The click element is positioned between said dose set knob and said setback member, said click element comprising a first arm member engaging an internal surface of said dose set knob, and a second arm member engaging an external surface of said setback member, wherein one of the said first and second arms produces an audible signal when said dose set knob is rotated with respect to said housing.
According to yet another exemplary embodiment of the present invention a medication injection pen is provided comprising a housing, for housing a dose set knob, a leadscrew, a driver, and a setback member. The dose set knob is rotatable with respect to said housing to set a desired injection dose. The leadscrew includes a thread element by which it is advanceable in a first direction via a corresponding thread engagement, said first direction being that which expels medication from a cartridge. The driver is rotationally fixed to said leadscrew for preventing relative rotation therebetween, said driver being rotatable in a first direction to rotate and advance said leadscrew in said first direction. The setback member is rotationally fixed to said driver for preventing relative rotation therebetween. The housing further comprises a flexible protrusion provided on a surface within said housing, and the dose set knob further comprises a flexible tab element which engages said protrusion to produce an audible signal upon completion of injection of a set dose.
Additional objects, advantages and salient features of exemplary embodiments of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with annexed drawings, discloses exemplary embodiments of the invention.
Throughout the drawings, like reference numerals will be understood to refer to like elements, features and structures.